1. Technical Field
This invention relates generally to gas turbine engines, and particularly to a gas turbine engine rotor disk-seal arrangement.
2. Background Information
Gas turbine engines such as those which power aircraft and industrial equipment employ a compressor to compress air which is drawn into the engine, a combustor for combustion of a mixture of compressed air and fuel, and a turbine to capture energy associated with the combustion of the fuel/air mixture. The compressor and turbine employ rotors which typically comprise a multiplicity of airfoil blades mounted on or formed integrally into the rims of a plurality of disks. The compressor disks and blades are rotationally driven by rotation of the engine's turbine. It is a well-known practice to arrange the compressor and turbine disks in a longitudinally axial stack in compressive inter-engagement with one another, which is maintained by a tie shaft which runs through axially-aligned central bores in the disks. The turbines of gas turbine engines typically incorporate alternating sets of rotating blades and stationary vanes. In this regard, it is commonplace to incorporate seals between adjacent sets of blades and vanes. Such seals prevent the leakage of cooling air injected into the interior of the rotor into the gas flow-path along which the vanes and blades are located. It is a well-known practice to mount such seals to cover plates (also commonly known as seal disks or mini-disks juxtaposed to the turbine's blade-retaining disks). Such seal disks are often provided with means for enhancing an adjacent disk's ability to retain to air foil blades mounted thereon. To minimize unwanted mechanical wear of the seal disks and the juxtaposed blade-retention disks, it is a known practice to provide an anti-rotation coupling of the seal disk to the blade retention disk. A well-known arrangement for such an anti-rotation coupling, involves the provision of an axially extending anti-rotation tab on either of the blade retention disk or seal disk which is received within a mating slot in the other of the blade retention disk and seal disk. To minimize rotor imbalances from such anti-rotation tabs, it has been the practice to provide such tabs in radially opposed pairs. It will be appreciated that pairs of such anti-rotation tabs may be beyond what is required to prevent rotation of these seal disks with respect to the juxtaposed blade retention disks and may contribute significantly to the weight of the combination of the blade retention disk and seal disk, thereby adversely affecting the efficiency of the engine. Accordingly, it has remained a challenge in the field of gas turbine engines to provide an anti-rotation coupling between a turbine blade retention disk and a juxtaposed seal disk which contributes minimally to the weight of a gas turbine engine turbine rotor.